Field of Invention
The present invention pertains to the technical field of paper containers, and particularly to a paper cup and its manufacturing process.
Related Art
A paper cup is a paper container fabricated by machining and bonding base paper made from chemical wood pulps. Existing technology of anti-scald paper cups is to sleeve an anti-scald layer, made of single layered paper with recessed or raised patterns pressed on it, over the inner cup made of single layered paper. There is also a corrugated anti-scald layer, where the face paper shrinks in proportion after being heated, and is molded and composited to the lining paper. It is then cut horizontally for wrapping around the paper cup to achieve the anti-scald effect.
One prior art paper cup comprises the cup body, cup bottom and the cup sleeve. The key point is that there is a cup sleeve sleeved over the cup body. The cup sleeve is made of corrugated paper. The corrugation strips are arranged horizontally, or recessed slots are set on the horizontally arranged corrugation strips. The manufacturing process is divided into two sub-processes of fabricating paper cup and fan-shaped sheet for corrugated paper cup sleeve, as well as an assembly process of cup sleeve fitting. The fan-shaped sheet for corrugated paper cup sleeve is rolled and molded by molds of the cup sleeve fitting machine. The joints are heat bonded by instantaneous ultrasonic heating, forming the corrugated paper cup sleeve. The inner wall is coated with glue and bonded to the paper cup. The crimping of the paper cup is single layered, and the strength is weak. In addition, the manufacturing process of fitting the cup sleeve over the cup body leads to a low bonding strength between the two parts. Hence, the supporting effect of the corrugations may fail when subjected to forces in use. However, the supporting strength of the paper cup when held in hand mainly comes from the crimping on the top. Therefore, this paper cup needs to thicken the paper sheet to remedy the defect of low strength. For this purpose, the weights of paper used for the cup body and the cup sleeve reaches 300 grams per square meter, and the manufacturing cost is relatively high. Moreover, the disadvantages of this manufacturing process also involves the addition of the die cutting and molding processes, the addition in the cost and thickness of the paper used for the anti-scald layer. They lead to a greater height when paper cups are stacked, increasing the volume, and costs of packaging, storage and transportation.